Repeater circuits



Ami? 115 19240 E. J. PRATT REPEAT'ER CIRCUITS Filed Sent. 28,

Patented Apr. 15,

U IT E D S T S 1,490,679 PATENT, OFFICE.

EDWARD J. rams-r, or new roux, 1c. in, ASBIGNOR 'ro mnc'rarc conrm,

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Application fledfleptember 28, 1822. Serial Io. 581,009.

Tocll whom it may concern:

Be it known that I, EDWARD J. PRATI, a citizen of United States, residing at New York, in the county of New Yorlr, State of New York, have inventedcertain new and useful Improvements in Repeater Circuits, of which the following is a full, clear,

concise, and exact description.

This invention relates to repeater circuits, particularly vacuum tube amplifier circuits. An object of this invention is to provide means whereby an electric discharge electrode and a transmitter may be simultaneouslysupplied with energizing current from a common source of voltage.

Another object is to provide a simple and eflicient arrangement for controlling the gain of a repeater. 4

In accordance with the embodiment of the invention disclosed, these objects may be accomplished by supplying a telephone transmitter and the cat ode of .an associated amplifier with energizing current from a common source of voltage. In series with the source of voltage an adjustable resistance may be included for the purpose of varying the current supplied to the transmitter and to the cathode whereby the effec- 'tiveness of the amplifier in amp ifying the currents impressed by the transmitter upon the amplifier may be varied. In case it is desired to employ a transformer between the transmitter and the control electrode and cathode of the amplifier for stepping up the impedance of the transmitter to an impedance approximating the input impedance of the tube amplifier, the primary and secondary windings of the transformer may have a common terminal so that the transmitter circuit will include the primary winding of the transformer, the adjustable resistance and the battery or other source of voltage, while another current path includes the said battery, the adjustable resistance and the cathode of the amplifier. If desired, the switch for varyin the adjustable resistance may be provide with an open circuit stationary contact, so that the movement of the switch arm to this contact simultaneously deenergizes the transmitter and the associated amplifier. The drawing illustrates this invention embodied in a one stage amplifier. 4 A vacuum tube or other electric discharge amplifier 7 is disclosed for impressing upon a telephone receiver 8 amplified currents from t 1e telephone transmitter 9. lhe control electrode 10 and cathode 11 of the amplifier 7 are connected to transmitter .9 by a step up transformer 12, the primary windmg of which is in circuit with transmitter 9 and the secondary winding of which is connected between t e cathode and the control electrode. The telephone receiver 8 is included between anode 14 and the cathode 11 by a circuit containing a source of voltage 15 for supplying the output circuit voltage to the amplifier.

This invention provides a circuit whereby the transmitter 9 and the cathode'll may be supplied with ener 'zing current from a common source of V0 ta e, such as source 16. Source 16 is connecte 'to transmitter 9 by a circuit including the primary windmg of transformer 12 and an adjustable resistance 17, contacts to various points on resistance 17 being made'by a movable switch arm 18. The source of voltage 16 is also included in circuit with the cathode 11 for supplying heating current to the same, and the amount of the heating current supplied may be regulated by a. variation in the position of switch arm 18 to cut in or out more or less of the resistance 17. This arran ement has been found to be a simple and e icient way of varying the gain of the amplifier 7 since considerable variation in the gain of a vacuum tube may be produced by variationsin th'e filament heating current without an appreciable amount of distor tion taking place. A variation in the efiective value of resistance 17 also varies the intensity of the energizing current supplied to the transmitter, thereby increasing still further the variation in the, amplification of tube 7 produced by a change in the posi- 'tion of the switch arm 18.

If desired, an open circuit stationary contact 19 maybe provided for switch arm 18 so that the switch arm 18 when in contact with contact 19 simultaneously deenergize's. the transmitter and the tube.

It is to be understood that this invention is not limited to any particular type of am lifier or transmitter, nor is the invention limited to an amplifier of a single sta e. It will'be obvious to those skilled in t .e art that various modifications of the above disclosure may be made'without departing in any wise from the spirit of t is invention as defined by the appendedclaims.

The inventlon claimed is: 1. In combination, an electric. d schar e repeater comprising an anode and a catho e,

at transmitter coupled to said repeater, an

energizing circuit for said transmitter, an energizing for said repeater, and an adjustable resistance common to both of said I ircuits. ,i

2. In combination, an electric dischar e repeater comprising an anode and a catho e,

a transmitter coupled to the input circuit of said repeater, an energizing circuit for said transmitter, an energizing circuit for said cathode, and an adpistable resistance common to both of said energizing circuits:

3. In combination, an electric dischar a repeater comprising anode, a catho e and a control electrode, a telephone transmitter, a transformer 'for couplin said transmitter to said control electro e and said cathode, a source of voltage, an ad- EDWARD J. PRATT. 

